This invention relates to a particular class of tertiary thiol ethoxylates and to a process for their preparation. More particularly, the invention relates to ethylene oxide adducts of higher carbon number (e.g., C.sub.9 to C.sub.16) tertiary thiols which exhibit improved detergency performance. The thiol ethoxylates of interest are characterized by a substantially reduced content of free thiols and lower ethylene oxide adducts, relative to their conventional counterparts.
A variety of products useful, for instance, as nonionic surfactants, solvents, and chemical intermediates, have been conventionally prepared by the addition of ethylene oxide to alkane thiols. An illustration of the preparation of a thiol ethoxylate (represented by formula III below) by addition of a number (n) of ethylene oxide molecules (formula II) to a single alkane thiol molecule (formula I) is presented by the equation ##STR1## wherein R is alkyl and n, representing the product's ethylene oxide adduct number, is an integer equal to or greater than one.
Of particular interest to the present invention are tertiary thiol ethoxylates in which the alkyl R group of the thiol ethoxylate molecule has a carbon number in the range from about 9 to about 16. These materials are known to have utility as components of detergent formulations and as spermicidal agents.
Any given ethylene oxide addition reaction is known to produce a mixture of various ethoxylate molecules having different numbers of ethylene oxide adducts (oxyethylene adducts), i.e., having different values for the adduct number n in formula III above. Tertiary thiol ethoxylate products prepared in this manner are, as a rule, sold and used in the form of such mixtures, having a statistical distribution of adduct numbers which is characteristic of the reaction, taking into account the relative amounts of reactants used. Such mixtures also characteristically contain a certain amount of unreacted (or "free") thiol. The conventional designation of thiol ethoxylates, in terms of ethylene oxide adduct number, represents a calculated average value for the number of ethylene oxide adducts per thiol ethoxylate molecule in the mixture.
The present invention most particularly relates to tertiary thiol ethoxylate mixtures having unique and beneficial ethylene oxide adduct distributions and low concentrations of free thiol.